Working with DivX and AVI files

Last edited:7 December, 2004
Author: Daniel Slagle

This site is NO LONGER being maintained for the "ALL NEW" site that talks about the new iMovie 11 please visit TheUnofficialiMovieFAQ.com

Note: If you
have a specific question on DivX or AVI files PLEASE do not e-mail me. I
do not personally use DivX or AVI file unless I have to. If you
have a specific question please visit the DivX or 3ivx forums.

What is an AVI file?

AVI is not a true file "format" it is a "container format".
Inside the file can be about anything, meaning it can contain video audio
compressed using many different combinations of codecs. So while MP3
and JPG can only contain a certain kind of compression (MPEG Audio Layer
3 and JPEG), AVI can contain many different kinds of compression (eg.
DivX video + WMA audio or Indeo video + PCM audio), as long as a codec
is available for encoding/decoding. AVI all look the same on the "outside",
but on the "inside", they may be completely different. Almost all tools
on this site are not just DivX tools, but also AVI tools, so will probably
work with other codecs.

There is no such thing as a "normal" AVI file, but the
closest you can get is probably an AVI file that contains no compression.
AVI files has been around since the time of Windows 3.1, so by no means
is it a new thing, and is probably the most common video format around
(although its popularity wavered a few years ago, but has since come
back with a vengeance due to the emergence of DivX). AVI files may also
have limits under Windows 95/98, and for more information, please read
this article. Note that AVI files without file limits (other than the
Windows Fat32 file limit) are usually referred to as OpenDML AVI files.

What is the easiest way to play AVI files on my Mac?

The first time you encounter an .AVI, QuickTime may open
the file, but all you see is a blank or sickly green screen, no audio,
and an error message. This means that you lack the necessary codecs/decoders
for proper playback.

Almost all files you will encounter have a video track
in some flavor of DivX with
an audio track encoded as VBR mp3, or lately, ac3. While QT can play
an .AVI with a CBR mp3 audio track, a VBR-encoded track will play with
a great deal of stuttering or drop out completely after a few seconds.

Some older files may have been encoded with MP42 or MP43,
two of Microsoft's earlier entries into the mpeg-4 field. Decoders available
here (missing link).

Still older files may have been encoded with one of the Indeo
codecs, none of which have been ported to OS X. If you wish to
view such a file, download the full set of Indeo codecs and install
in QT in OS 8/9. Regarding Indeo compression, there is a QT decoder
for Indeo 263 (I263) that has worked for me in OS 9 and lower. The
author says he doesn't know if it works in OS X and I have not tried
it there either, but here is
the link for the decoder.

Here are the most common solutions:

Use an alternative player, such as VideoLAN
Client (aka VLC) or MPlayer,
both UNIX players now ported to OS X. If a file does not play properly
in one of these players, then your chances are slim of ever getting
the file to play on a Mac.

Download DivX Doctor
II, the 3ivx
codec, and the .wma
decoder and install as directed. Use DivX Doctor to convert
the .AVI into a .MOV. Note: DivX Doctor is extremely intolerant
of errors and sometimes creates a .mov file with bad synchronization.

Purchase the trial or pro version of the DivX
5 package, which contains an MP3 decoder for AVI's to play
natively in QT. The free version does not contain the MP3 encoder
and allows you only to encode a DivX video track in a .MOV

Note: If 3ivx and DivX 5's video codec are installed
at the same time, 3ivx will take precedence, though the mp3 component
will work flawlessly. If you wish DivX 5 to decode the video track,
then remove the 3ivx component from the QuickTime library folder
and restart QuickTime.

Are all AVI files DivX?

No, although 95% or more are today, due to the fact it
is used in the popular (and PC-centric) peer-to-peer groups.

What is 'doctoring' an AVI file, and do I need to do it?

Quicktime adheres to the AVI standard. The problem is that
AVI files with VBR MP3 audio tracks are not supported (it's a hack to
the AVI format), so you get no sound or very stuttering sound when you
try to play it. DivX Doctor works by correcting the audio information
and sticking it in a Quicktime movie file with the video.

Why might you still want to do this after DivX's AVI Importer
came out?

Streamable

As many audio/video/text/flash tracks as you want

Metadata

Chapter tracks

A, relatively, open format that is ludicrously easy to edit and
convert

What does DivX Doctor do to an AVI file?

DivX Doctor II first extracts the audio track, then the video,
then, in QuickTime Pro terms, adds, rather than adds-scaled, the video
to the audio. If you save as a dependent file, the Doctor creates a .MOV
with the entire audio track but with a link to the video of the original
.AVI

If the "flattening" process takes too long or
hangs indefinitely, try saving as dependent, then opening this file with
QT Pro and saving again as self-contained movie.

Sometimes the
Doctor produces bad synchronization

Solution 1: Open the .mov file the Doctor has produced.
Extract both tracks, and add-scaled the video to the audio. Save as self-contained.

Solution 2: If the synchronization is still off, but consistently
so, use QTMutator. For
more serious problems, use SyncHole.

I get an error message
in DivX Doctor, "Audio may be truncated", but the file
plays fine in VLC. Can I fix this movie?

You can extract the audio track yourself using DivX Tool(link)
or the pass-through option of ffmpegX (see below). Then in QuickTime
Pro, follow the steps outlined above in Solution 1.

DivX Doctor refuses to convert an .avi, it won't open in QuickTime, but
it plays in vlc. How can I view this movie in QT?

The file may have been mislabeled, in which case, it could
be anything (.RM, .ASF, WMA, MPG (MPEG), etc.). Try the info feature
of DivX Tool or ffmpegX.
If all else fails, open the file with a Hex Editor. If it is an .AVI,
then the header will begin with RIFF.

If you see the progress arrow in VLC move slowly to the
right before playback, this means that the index of the AVI is corrupted
or faulty. While VLC can reindex on the fly, QT requires this information
intact.

The index is a footer at the end of the file and contains
timing information necessary for playback. A .mov has a much smaller
header, which is why a doctored .avi>.mov file is always smaller in
size than the original.

You can reindex an .AVI in several ways;

Use the "fix" option in DivX Tool.

Use pass-through options on both audio and video
tracks in ffmpegX, then discard the original.

If you have installed ffmpegX or
any other GUI to MEncoder,
then you can use the terminal:Open the Terminal app and after log-on,
type:

What additional codecs can I use or will I need?

Why is there no sound on the DivX file I made from a QT movie using ffMpegX?

I am trying to make a DivX version of the QT movie I have
edited iniMovie. I exported the movie as full sized version but after
encoding I have no sound when played in Mplayer.

If you are using QT as your player, you will have to "Doctor" the
file. See XXXX. Mplayer or VLC player offer you playback in OSX with
out this procedure. If your problem persists, read below.

When setting up your encoding from a Quicktime movie, you
have a choice of audio tracks. The default is track 1. However, Quicktime
sometimes uses track2. So if you have no sound, select track 2 and try
a 5 second encoding session to so if that fixes the problem.

Other problems can arise if you select the wrong audio
setting for the sound option under the QT export. Make sure it is Stereo,
and 44 or 48Khz.